1156
BLOMQUIST AND
HIMICS
The Journal of Organic Chevnistry
Terpene-Formaldehyde Reactions. 11. d-Limonene’ A. T. BLOMQUIST
AND
RICHARD J. HIMICS~
Department of Chemistry, Cornell University, Ithaca, New York 14860 Recetved October 18,1987 Reaction of d-limonene with formaldehyde to give a simple 1: 1 product is best achieved in solvent methylene chloride-acetic anhydride at autogenous temperature for 70 min under nitrogen at 1 atm with a complex of boron trifluoride as catalyst, preferably the dihydrate. The principal product fraction (82% yield) is comprised mainly of (84%) 9-acetoxymethyl-1,8( 10)-p-menthadiene. This acetate and its alcohol are easily converted into the saturated primary alcohol 9-hydroxymethyl-p-menthane. The acrylate of the latter alcohol gives a homopolymer and a methyl methacrylate copolymer when polymerized in bulk with initiation by azobisisobutyronitrile.
There are many reports in the literature concerned with the reaction of d-limonene, or dipentene, with f~rmaldehyde,~ but none describes the isolation and unequivocal characterization of pure 1:1 reaction products, or simple derivatives thereof. With the modern experimental methods for isolation, purification, and characterization of organic compounds now available, e.g., analytical and preparative glpc, nmr spectroscopy, etc., it was of interest to make a careful, extensive study of the limonene-formaldehyde reaction. The useful synthesis of a primary alcohol from readily available pure d-limonene is of importance also. The limonene-formaldehyde reactions described in this report are those (a) catalyzed by Lewis acids, (b) catalyzed by mineral or strong acids, and (c) so-called “noncatalyzed” thermal condensations. Reactions of the type a proved to be the most broadly useful. Treatment of lcl-limonene with paraformaldehyde (PFA) (2 :1 mole ratio) in methylene chloride containing fuming stannic chloride (0.1 m1/0.22 mol of PFA) for 2 days at room temperature gave, after distillation, a 49% yield of an alcohol fraction that was comprised mainly (8045%) of the alcohol Q-hydroxymethyl-1,8(10)-p-menthadiena (1) and not the alcohols 2a and/ or 2b. The pure alcohol 1 was obtained by preparative glpc followed by redistillation. The minor products (15-20%) were not examined. The ir spectrum of the pure alcohol 1 had bands a t A,, 3.0 (OH), 6.97 (internal double bond), 6.09 (>C=CH2), 9.55 (primary OH), 10.90 (internal double bond), and 11.27 p (>C=CH2). The nmr spectrum is indicated in Chart I. The triplet at T 7.74 (-CH&H20H) wa,s isolated from the other proton signals in the nmr by observing the nmr spectrum of the 3,5-dinitrobenxoate derivative, mp 79.5”, of the alcohol 1 (see Experimental Section), which clearly showed the presence of the group -CH&H20CO-. The alcohol 1 was converted easily into its acetate, 9(1) For the preceding report from this laboratory on olefin-formaldehyde reactions, see A. T. Blomquist and J. D. Meador, J . Oro. Chem., 84, 3986 (1967). (2) Abstracted from part of the Ph.D. Dissertation of R. J. Himics, the Graduate School of Cornell University, Ith8C8, N. Y., Feb 1967. (3) (a) G . Ohloff, Arch. Pharm., 387, 259 (1954); (b) A. T. Blomquist, J. Verdol, C. L. Adami, J. Wolinsky, and D. D. Phillips, J . Amer. Chem. SOC,, 79, 4876 (1957); (e) K. suga, A. Matsuda, and 9. Watanabe. Nippon Kauaku Zaashi, 79, 724 (1958); Chem. Abstr., 64, 4656 (1960); (d) Y, Matsubars and Y. Watanabe, ibid., 80, 651 (1959); Chem. Absfr., 56, 3464 (1961); (e) Y. Watanabe, ibid., 80, 1063 (1959); Chsm. Absfr., 56, 3591 (1961); (f) y. Watanabe, Y. Matsubaia, and C. Huang, Kouyo Kaoaku Zasshi, 64, 1630 (1959); Chsm. Abstr., 67, 13963 (1962); (g) J. Colonge and J. Crabalona, Bull. SOC. Cham. Fr., 102 (1960); (h) K. Bugs and 8. Watanabe, Chiba Daioaku Kopakuba Kcnkyu Hokoku, 11, 29 (1960); Chem. Absfr., 56, 21159 (1961); K. Suga and S. Watansbe, Nippon Kogaku Zasshi, 81, 1139 (1960); Chem. Abefr., 66, 507 (1962).
CHARTI
-
CH3 r 8.40
x
+(CHiO)z
in CHzClp
CH3r 8.39 & H r 4 . 6 9
x
T
6.38
CHz’
CHs
CHz’
CHz/CH2\0H
76.43
~8.31
~5.25
T
7.74
1
CHzOH
2a
x
2b
acetoxymethyl-l,8(10)-p-menthadiene (3), with acetic anhydride. A set of boron trifluoride complexes proved to be very interesting catalysts for the reaction of the title compounds. Thus, reaction of a 2 : l mixture of dlimonene and formaldehyde in the solvent system methylene chloride-acetic anhydride (1 :1 volume ratio) at autogenous temperature (25-45’) for 70 min and catalyzed by boron trifluoride dihydrate gave an 82% yield of acetates, 84% of which was the acetate 3. Careful redistillation of this product gave the compound 3 in purity greater than 96%. Under similar conditions the reaction was catalyzed by (a) boron trifluoride etherate, (b) boron trifluoride diphenol, and (c) boron trifluoride diacetic acid to give product acetates in yields of 80, 82, and 78% (with the acetate 3 content found to be, respectively, 80, 88, and 85%). Reaction times for the three reactions were 140, 110, and 60 min at autogenous temperature. Boron trifluoride etherate and diphenol catalyzed reactions of limonene and formaldehyde in the simple solvent methylene chloride afforded decreased yields (47-5993 of product alcohols that contained ca. 75430% of the alcohol 1. In the latter reactions there was always obtained a substantial amount of higher boiling material. Two components of the high boiling product obtained in the boron trifluoride etherate catalyzed reaction were isolated by careful distillation and column chromatography. Nmr and infrared analyses indicated that they were the ether 4 and the formal 5 (see Experimental Section). The formation of accessory products such as 4 and 5 is clearly reduced in the solvent system methylene chloride-acetic anhydride, probably the consequence of the rapid trapping of alcohols as acetates. The limonene-formaldehyde reactions catalyzed by acids such as phosphoric, formic, dichloroacetic, and p-
TERPENE-FORMALDEHYDE REACTIONS1157
Vol. 33, N o . 3, March 1968 CH3 I 8.38
28.38 CH3
&HT4.66
M . 4 . 6 6
25.27
CHs T
77.75
4
CHa
x
~8.87
r 5.43
r 6.42
CH2/
C H z / C H ~ \ ~ / ~ C H z \ O / C HT6'42 z\CH1
25.23
r 7.12
x C H 2
r1.12
I
5.23
5
toluenesulfonic were flound to be unpromising in that they all afforded inferior yields of complex mixtures of products. Thus, the phosphoric acid-catalyzed reaction in acetic acid-acetic anhydride at 5-15' gave a 34% yield (as acetates) of a mixture that glpc analysis indicated to be composed of three major and at least six minor compounds the formic acid catalyzed reaction in glacial acetic acid at 95-100' afforded a 44% yield of a product mixture that was comprised of three monoacetates in about equal amount (glpc analysis). For the sake of completeness the classical "noncatalyzed" thermal condensation of d-limonene with formaldehyde was reexamined. Reactions effected in a sealed autoclave at 180-20O0 under autogenous pressure in a variety of solvent systems were uniformly unsatisfactory; all afforded in low yield a complex mixture of products (glpc analysis) whose principal component was the alcohol 1 or the acetate 3, Reactions in acetic acid in an open vessel at temperatures that ranged from 110 to 125' for 1-7 days gave ca. 40-70% yields of complex mixtures whose principal component (55-80%) was the acetate 3. With the alcohol 1 and its acetate 3 available in high yield and purity from d-limonene it was of interest to examine briefly the polymerization of the saturated primary alcohol 9-hydroxymethyl-p-menthane (6) derivable from either 1 or 3. Catalytic hydrogenation of the alcohol 1 occurred smoothly, and stepwise, to afford the alcohol 6 as an inseparable mixture of the expected cis and trans isomers. The intermediate product of hydrogenation, 9-hydroxymethyl-1-p-menthene(7),
7 C H s r 9.02-9.13
1
CHI T9.02-913
8
was obtained by interrupting the hydrogenation after 18 hr (see Experimental Section). Transesterification of methyl methacrylate with the saturated alcohol 6
gave the desired ester 8, of purity >99%, suitable for polymerization. The homopolymer of the methacrylate 8 together with a copolymer of 8 and methyl methacrylate were obtained smoothly t.ia bulk polymerization initiated by azobisisobutyronitrile. The two polymers, mp 225-230' and 215-225', respectively, differed markedly in their ease of handling; the homopolymer was soft, caked on standing, and acquired a static charge when ground; the copolymer was a hard, white solid that was easily pulverized. Both polymers were soluble in benzene or toluene and insoluble in acetone or methanol. They showed an intrinsic viscosity in benzene of 3.72 and 3.69 dl/g, respectively.
Experimental Section4v6 Materials.-The d-limonene used was purchased from Eastman Kodak and showed a purity greater than 99% by glpc analysis.68 Fisher "trioxymethylene" (USP) was used as a formaldehyde source; the boron trifluoride catalysts were obtained from the General Chemical Division of the Allied Chemical Corp. The Stannic Chloride Catalyzed Reaction of d-Limonene with Paraformaldehyde.-A mixture of 62.2 g (0.457 mol) of dlimonene, 6.6 g (0.22 mol) of paraformaldehyde (PFA), and 400 ml of dry methylene chloride was stirred under nitrogen for 10 min. Fuming stannic chloride (0.3 ml) was then added over 0.5 hr and the mixture stirred at room temperature for 2 days. To the clear, tan solution that resulted there was added, with vigorous stirring, ca. 20 ml of cold, dilute sodium hydroxide. The separated aqueous layer was extracted with ether and the ether extracts were combined with the methylene chloride layer. From the dried (MgSOd), combined ether-methylene chloride solution, after removal of solvents in vacuo, there was obtained upon distillation two product fractions: (1) 18 g, bp 89-95' (0.5-0.6 mm), 7LBD 1.4991; (2) 3 g, bp 87-144" (0.3 mm), n 2 3 ~ 1.5086. Fraction 1 (49% yield for a 1: 1 limonene-formaldehyde reaction product) was a clear, colorless liquid of 80-S5% purity (glpc analysis).6b Fraction 2 was not immediately examined. 9-Hydroxymethyl-1 ,S(lO)-p-menthadiene (l).-Fraction 1 described above (ca. 4 ml) was purified via preparative glpc on an 8-ft column (30% Versamid 900 on Chromosorb W ) at 180'. Other conditions for the glpc purification were sample size, 1 ml; injector temperature, 330"; detector temperature, 310"; traps manifold, 300'; back pressure value, 310"; head pressure, 15 psi; back pressure, 0 psi; attenuation, 8; flow rates, 7 cm (rotameter). The resulting product, contaminated with Versamid 900, gave the pure alcohol 1 upon redistillation, bp 80-83' (0.2-0.3 mm) and n * *1.4986. ~ Its ir spectrum showed significant absorptions at 3.0, 5.97, 6.09, 9.55, 10.90, and 11.27 p . The nmr spectrum showed the following assigned values: T 4.69 (s, >C=CH-), 5.25 (m, >C=CHz), 6.38 (t, -CHZ-OH, 7 cps), 7.74 (t. -CH&HzOH, 7 cps), 8.08 (bs), and 8.39 (s, CHsC=CC=CH), 5.25 (br S, -C=CHz), 5.92 (t, -CH&O-, 7 Cps), 7.71 (t, -CHzCHzOzC-, 7 CPS),8.09 (6, -0&CHa), and 8.41 (>C=CCHa). Anal. Calcd for C13H2002: C, 74.96; H, 9.68. Found: C, 75.17; H , 9.79. The 3,5-dinitrobeuzoate derivative of 1, prepared via treatment of 1 with 3,5-dinitrobenzoylchloride in the presence of pyridine, mp 79.5' (ethanol-.water) showed significant ir absorptions at 5.80 and 8.55 p ; its nmr spectrum showed peaks at 7 2.7 (s, aromatic), 4.6 (br , -C=C(H)-), 5.13 (br s, -C=CHz), 5.4 (t, --CHzCO-, 7 CPS , 7.4 (t, -CHZCHZOZC-,7 cps), 7.95 (br s), and 8.4 (s, >C=CCHa). Anal. Calcd for C18H20N206: C, 59.99; H, 5.60; N, 7.78. Found: C, 59.98; II, 5.81; N, 7.54. The phenylurethari derivative of 1, prepared in a conventional way, had mp 56-57' (from petroleum ether, bp 90-110') and showed significant ir absorptions a t 3.01 (>NH), 5.89 (-CONC=CH), 5.22 ( s , >C=CHz), 5.28 (t, -CH20zC-), 7.69 (t, -CHzCHzOzC-), 8.05 (m), and 8.38 (13, >C=CCHs). Anal. Calcd for C~~HIZNOZ: C, 75.75; H, 8.12; N, 4.91. Found: C, 75.87; I€,8.04; N , 4.95. Reaction of d-Limonene with Paraformaldehyde Catalyzed by Boron Trifluoride Complexes. I. With Boron Trifluoride Etherate. A. In Solvent Methylene Chloride.-A solution of 1.0 ml of boron triHuoride etherate in 60 ml of dry methylene chloride was added over a 20-min period to a stirred mixture of 90.5 g (0.665 mol) of d-limonene, 9.9 g (0.33 mol) of PFA, and 300 ml of dry methylene chloride a t room temperature under nitrogen. This mixtiire was stirred for 1 hr, treated with 20 ml of sttturated sodium bicarbonate solution, and worked up in a conventional way to give a 47%, yield (26 g) of the alcohol 1, bp 81-91" (0.30 mm) aiid n Z 61.4964, ~ of about 807, purity (glpc analysis). B. In Solvent Methylene Chloride-Acetic Anhydride.-A solution of 1.0 ml of boron triHuoride etherate in 90 ml of a 1: 1 by volume mixture of methylene chloride and acetic anhydride was added to a stirred mixture of 45.2 g (0.332 mol) of d-limonene, 5.00 g (0.166 mol) of PF.4, 75 ml of methylene chloride, and 75 ml of acetic anhydride at room temperature under nitrogen. After a total reaction time of 142 min (reaction temperature rose to 36" before subsiding) the mixture was worked up in a conventional way to give three principal fractions upon distillation: (1) 19.1 g, bp 35-50" (5.5 mm), n Z 51.4680; ~ (2) 27.6 g, bp 58-93' (0.26 mni), nZ5D1.4778; (3) 6.37 g, bp 98-148' (0.25 mm), n Z 51.4845. ~ Fraction 1 wm recovered d-limonene and corresponded t,o 84.5% of the excess used. Fraction 2 represented an 80Y0 yield of the expected limonenyl carbinol acetate 3 of ca. 80Yc purity (glpc analysisbd). 11. With Boron Trifluoride Diphenol. A. In Solvent Methylene Chloride:-A solution of 5 ml of boron trifluoride diphenol in 95 ml of dry methylene chloride was added over a 45-min period to a sirred mixture of 90.5 g (0.733 mol) of dlimonene and 9.9 g (0,33mol) of PFA in 300 ml of dry methylene chloride a t room temperature under nitrogen. The mixture was stirred for another hour, and, after a conventional work-up, gave on distillation unreacted d-limonene together with two principal product fractions: (1) 32.5 g, bp 84-91' (0.35 mm), n Z 61.4949, ~ and (2) 17.5 g, bp 140-170" (0.20 mm), n% 1.5040. Fraction 1 represented a 59% yield of the alcohol 1 of purity 75% (glpc analysis5e). Fraction 2 was comprised of high boiling alcohols and ethers. Upon repetition of the reaction described above using 3.0 and 7.0 ml of catalyst the impure alcohol 1 was obtained in 53 and 497, yield, respectively. The high boiling product, bp 100-190' (0.15-0.40 mm) and nZ5D 1.5028-1.5055, was obtained in substantial amount in all three reactions. Z,lO-Bis(4'-methyl-3 '-cyclohexenyl)-5,7-dioxa-l, 10-hendecadiene (5).-Examination of the combined high boiling product fraction obtained in the three reactions described in the preceding section (glpc and infrctred analysis of redistilled fractions) indicated that it was composed of ca. 25% of the alcohol 1 and ca. 42% of a complex mixture of alcohols and ethers. Redistillation
,
of a fraction of bp 137-168' (0.20 mm) gave a fraction, bp 152153' (0.15 mm), whose ir spectrum showed a trace of an hydroxylic component. Column chromatography over neutral alumina with petroleum ether (bp 30-60') as eluent removed this impurity. Careful redistillation of the chromatographed ma1 terial gave a center-cut, bp 147-148' (0.15 mm) and n z 6 ~.5029, whose properties indicated it to be the formal 5. I n the infrared it showed strong absorption maxima a t 6.10 6.94, 7.26, 9.0, 9.3, 9.7, 11.2, and 12.5 p ; its nmr spectrum showed absorptions at T 4.61 (br s), 5.25 (br s), 5.43 (s), 6.42 (t), and 8.37 (br s). Anal. Calcd for Cz3H36OZ: C, 80.18; H, 10.53; mol wt, 344.52. Found: C, 79.99; H, 10.46; mol wt, 345 (chloroform). 2,6-Bis (4'-meth yl-3 '-cyclohexenyl)-6-methyl-5-oxa-l-heptene (4).-From the high boiling fraction described at the beginning of the preceding section there was obtained, after redistillation, a lower boiling component, bp 124-126' (0.15 mm). This fraction was chromatographed over neutral alumina, benzenepetroleum ether (bp 30-60') eluent, and redistilled to give a center cut (bp 124-124.5' (0.10 mm) and n Z 51.5019) ~ whose spectral properties were in agreement with the ether structure 4. I n the infrared it showed significant absorption maxima a t 5.98, 6.90, 7.23-7.33, 9.33, 11.23, and 12.49 p . The nmr spectrum showed absorptions a t T 4.66 (br s), 5.27 (br s ) , 6.62 (t), 7.79 (t), 8.38 (br s), and 8.94 (s). Anal. Calcd for C21H340: C, 83.38; H , 11.33; mol wt, 302.48. Found: C, 83.35; H, 11.46; mol wt, 310 (acetone). B. In Solvent Methylene Chloride-Acetic Anhydride .Reaction was carried out as described in section I B above. A mixture of 46.3 g (0.34 mol) of d-limonene and 4.8 g (0.16 mol) of PFA in 100 ml of methylene chloride and 100 ml of acetic anhydride, to which had been added 1.0 ml of boron trifluoride diphenol in 53 ml of the mixed solvent, was stirred under nitrogen a t autogenous temperature. The usual work-up gave 27.0 g of a distilled product fraction (bp 87-96' (0.20-0.25 mm) and n z 6 1.4780) ~ and corresponded to an 81.5y0 yield of the acetate of a 1 : 1 reaction product. Glpc analysis5' showed that it contained 88.57, of the acetate 3. 111. With Boron Trifluoride Dihydrate.-The procedure outlined ill sections I B and IIB was followed. From 53 g (0.39 mol) of d-limonene and 5.7 g (0.19 mol) of PFA in 100 ml each of methylene chloride and acetic anhydride to which 0.40 ml of boron triHuoride had been added there was obtained, after a total reaction time of 70 min, 32.4 g (82%) of a distilled product fraction (bp 90-102' (0.40-0.45 mm) and n Z 51.4775) ~ that was found by glpc analysis6d to be composed mainly (847,) of the acetate 3. Three redistillations of this product gave a sample of 3 (purity >967, by glpc analysis5d)whose ir and nmr spectra as well as elemental analysis were in accord with those given previously for 3 (supra vide). The Phosphoric Acid Catalyzed Reaction of &Limonene with Paraformaldehyde.-To a stirred mixture of 100 g (0.735 mol) of d-limonene, 25.5 g (0.750 mol) of PFA, 160 ml of glacial acetic acid, and 25 ml of acetic anhydride cooled to 5' there was added a solution of 25 g of phosphoric acid in 25 ml of acetic acid over a 2-hr period. Stirring was continued at 5-15' for an additional 6 hr and the mixture than allowed to stand overnight. Work-up of the reaction mixture gave unreacted limonene (10.15 g) and three principal product fractions: (1) 1.11 g, bp 3 0 4 0 ' (0.15 mm), n z 3 ~1.4835; (2) 4.5 g, bp 45-47' (0.10 mm), n23~ 1.4775; (3) 46.70 g, bp 50-70' (0.10 mm), n Z 31.4868. ~ All three fractions showed very similar infrared spectra with strong absorptions a t XmBx 2.94, 3.42, 5.81, 7.04, 7.94-8.32, 9.52-9.70, 11.3, and 12.5 M. The fractions 2 and 3 represented a 34Y0 yield of acetates (such as 1) derived from limonene. Glpc analysis5g of fraction 3 indicated that it consisted of three major and at least six minor components. The Formic Acid Catalyzed Reaction of d-Limonene with Paraformaldehyde.-From a mixture of 89 g (0.655 mol) of dlimonene, 9 g (0.30 mol) of PFA, 10.5 g of 98-10070 formic acid, and 250 ml of glacial acetic acid stirred for 1-3 days at 95-100' there was obtained two principal product fractions: (1) 27.3 g, bp 78-98' (0.40-0.45 mm), n Z 51.4752; ~ (2) 15.0 g, 1.4820. Fraction 1 amounted to bp 120-135' (0.40 mm), n 2 5 ~ a 44y0 yield of a mixture of three monoacetates. Glpc analysis6h indicated that the three components were present in about equal amounts. Thermal Reactions of &Limonene with Paraformaldehyde. A. In a Sealed Autoclave.-A mixture of 313 g (2.37 mol) of d-limonene, and 62.4 g (2.08 mol) of PFA was heated with shaking far 10 hr a t 175-185' in a 4-l., stainless steel bomb. The
Vol. 3, No. 3, March 1968
TERPENE-FORMALDEHYDE REACTIONS1159
Methacrylates of the Alcohols 1 and 6. A. 9-Hydroxycooled, clear product was taken up in ether, washed with water, methyl-l,8( 10)-p-menthadiene Methacrylate.-The procedure and dried (MgS04). Upon distillation there was obtained 194 g of Burtle and Turek6 was used. From 8.3 g (0.05 mol) of the of d-limonene and three principal product fractions: (1) 11.8 alcohol 1 there was obtained 10.5 g (4570) of the methacrylate g, bp 71-95' (0.35 mm), n n ~ 1.4891; (2) 72.3 g, bp 94-95' derivative, bp 90-93' (0.15 mm) and n Z 41.4900. ~ Glpc analysis6n (0.35 mm), n * ' ~1.4845; (3) 21.0 g, bp 110-132' (0.20 mm), of a redistilled sample of the ester showed but one component. TPD 1.5029. The undistilled residue was 22.3 g. The combined Significant ir absorptions were observed a t 5.8-5.9, 6.10, 8.4fractions 1 and 2 represented a 24.4y0 yield of an alcohol such as 8.7, and 11.18 p . The nmr spectrum had peaks at T 4.03 (m, 1; glpc analysis,&dshowed that it was comprised of four major -(CHaC=C(H)-), 4.59 (m, -(CHa)C=C(H)-), 4.70 (s, >C= components in a 9:3:2:1 ratio. The two fractions had similar CH-), 5.25 (m, >C=CHZ), 5.86 (t, -CHZOZC-), 7.70 (t, ir spectra: ,A, 2.96, 3.40, 5.71, 6.03, 6.87, 7.28, 8.44, 9.49, -CH2CH20-), 8.17 (t, -(CHa)C=CHz), and 8.45 (-(CHa)C= 10.85, 11.16, and 12.43 p as well as 5.71 and 8.44 p indicative CH-) . of formate ester. Fraction 3 showed strong ir absorptions for alcohol and ester groups but since glpc analysis61 gave ill-defined B , 9-Hydroxymethyl-p-menthaneMethacrylate (8).-Transesterification of 27.2 g (0.26 mol) of methyl methacrylate with peaks i t was not examined further. 18.6 g (0.108 mole) of the alcohol 6 in the presence of 0.3 g of A mixture of 300 ml of anhydrous methanol, 1.5 g of dibutyl sulfuric acid and 1.0 g of cupric acetate was carried out at 100' tin oxide, and 72 g of fraction 2, estimated by glpc analysis to for 16.5 hr. During this period material of bp 55-64' was recontain ca. 14.5 g (0.0732 mol) of formate ester, was heated moved intermittently. Work-up and distillation of the mixture for 2 hr a t 70-75'. Distillation of the reaction mixture gave three principal product fractions: (1) 5.6 g, bp 60-78" (0.20gave two principal product fractions: (1) 1.2 g, bp 50-80' 0.10 mm), n% 1.4945; (2) 40.6 g, bp 78-78.5' (0.05 mm), (0.25 mm), 1 2 2 6 ~ 1.4680; (2) 20.5 g, bp 97--104' (0.25 mm), n% 1,4660. Fraction 2, which corresponded to an 81% yield n z 6 1.4980; ~ (3) 18.0 g, bp 68-73' (0.025 mm), n = D 1.4995. Infrared analysis showed that fraction 1 contained a trace of of the desired methacrylate, gave after redistillation a center cut, formate ester whereas fractions 2 and 3 were formate free; the ~ of purity >99% (glpc analy(bp 90' (0.35 mm) and n Z 61.4662) si@). The ir spectrum of the latter showed Am,, 3.51, 5.91, latter spectra were similar. The ir spectrum of the major fraction 2 was identical with 7.65, 7.82, 8.62, 10.8, and 12.8 p ; nmr peaks were at T 3.94 that of "homolimonenol," ( n z 7 1.4988) ~ previously rep~rted:~b and 4.52 (d, >C=CH2), 5.85 (t, -CHzOzC-), 8.09 (d, -(CHa)CAm., 2.98, 3.49, 6.05, 7.01, 7.25, 9.5-9.9, 11.25, and 12.5 p . =CHz), 9.02-9.13 (m, saturated CHI-). In addition, glpc analysis6i of this fraction showed that it was Anal. Calcd for Cz5H2602: C, 75.58; H , 11.00; mol wt, identical with an authentic sample of "homolimonenol" and 238.36. Found: C, 75.62, 78.51; H, 11.01, 11.08; mol wt, that it was comprised of ca. 75-807, of the limonenyl carbinol 1. 241, 238 (benzene). When the d-limonene-formaldehyde experiment described Polymerization of the Methacrylate of the Alcohol 6. A. above was carried out in the presence of added sodium acetate Homopolymerization.-Bulk polymerization of the methacrylate (0.01 mol/O.lO mol PFA) no appreciable reaction occurred. 8, initiated with azobisisobutyronitrile, was carried out at 4 7 4 8 ' Recovery of the initially charged limonene was ca. 8870. for 3 days. The initially formed (83%) clear, glassy polymer B. At Atmospheric Pressure.-A mixture of 81 g (0.50 mol) was soluble in benzene and toluene; insoluble in chloroform, of d-limonene, 9.0 g (0.30 mol) of PFA, and 300 ml of glacial acetone, and methanol.' (It was difficult to pulverize and dry acetic acid heated at 98-101' for ca. 2 days gave, after the usual the polymer because of its tendency to acquire a static charge.) The dried, rather soft polymer showed mp 225-230". Its work-up and distillation, two principal product fractions: ( 1 ) 8.39, bp 78-83' (0.35 mm), n Z 6 D 1.4748; (2) 26.0 g, bp 88-93' intrinsic viscosity in benzenes was 3.72 dl/g of polymer. The ir (0.35 mm), ED 1.4780. Glpc analysis of fraction 2Sk showed spectrum of the polymer as a film, obtained on slow evaporation that it consisted primari1.y (ca. 80%) of a single component, the of its benzene solution, showed signals at Amax 3.5, 5.8, 7.9. expected acetate 3. This was confirmed by comparison of its ir 8.5-9.9, and 12.5 p . spectrum and refractive index with those of an authentic sample Anal. Calcd for (Cl6H2&),: C, 75.58; H, 11.00. Found: of 3. C. 75.71. 75.29: H. 11.24, 11.32. &,trans-9-Hydroxymethyl-p-menthane (6).-Catalytic hydroB. ' Copolymerization with Methyl Methacrylate.-Bulk genation, in a Parr apparatus, of 23.0 g (0.138 mol) of the polymerization of 1.85 g of the methacrylate 8 and 2.0 g of methyl alcohol 1 in 80 ml of ethyl acetate over 0.8 g of Adams catalyst methacrylate (28.3:71.7 mole yo ratio), initiated with 0.04 g of under 3 5 4 5 psi of hydrogen for 36 hr at room temperature gave azobisisobutyronitrile, was effected at 50' for 24 hr. The crude 21 g (88%) of the saturated alcohol 6, bp 70-77' (0.30 mm) and polymer was dissolved in warm chloroform, the filtered solution n 2 5 1.4692. ~ Glpc analysis6' indicated that the product consisted added to methanol, and the precipitated copolymer collected of two major closely eluting components together with a small and dried at 100' in uacuo. The reprecipitation and drying were amount of a lower boiling compound. I r analysis indicated the repeated twice to give 3.29 g (85.570) of the copolymer as a absence of unsaturated and ester materials. white tractable powder, mp 215-225", whose intrinsic viscosity Anal. Calcd for C11H:tzO: C, 77.58; H, 13.02. Found: C, in benzene was 3.69 dl/g of polymer. Elemental analysis in77.53; H, 12.91. dicated that the polymer was indeed a copolymer of 8 and methyl Column chromatography of the alcohol 6 over neutral alumina methacrylate. did not effect separation of the cis and trans isomers. Anal. Found: C, 67.96, 67.81; H, 9.52, 9.70. A similar hydrogenation of 25.4 g of the alcohol 1 in 100 ml of absolute ethanol over 0.35 g of platinum black for 2 days gave Registry No.-d-Limonene, 5987-27-5 1, 15766-66-2 ; 24.4 g (92%) of 6 (bp 85-!33' (0.45 mm) and n Z 61.4692) ~ identical 1 3,5-dinitrobenzoate, 15766-67-3; 1 phenylurethan with the alcohol described above. derivative, 15766-68-4; 3, 6819-19-8; 4, 15815-76-6; 5, 9-Hydroxymethyl-1-p-menthene(7).-Catalytic hydrogena15760-15-3; 6 (cis), 15760-16-4; 6 (trans), 15760-17-5; tion of 20.3 g of the alcohol 1 in 100 ml of absolute ethanol over 0.3 g of platinum black for 18 hr, under 22-39 psi of hydrogen 7, 15760-18-6; 8, 15760-19-7; 9-hydroxymethyl-l,8(10)gave two principal product fractions: (1) 14.8 g, bp 80-90' p-menthadiene methacrylate, 15760-20-0. (0.4 mm), n2% 1.4800, (2) 3.4 g, bp 91-92' (0.4 mm), n z e J ~ 1.4837. Glpc analysissm showed that fraction 2 was ca. 95% Acknowledgment.-This study was carried out under pure 7. Ir and nmr analysis were in support of the proposed Contract No. 12-14-100-6884(72) with the Southern structure 7: Am,, 3.04, 3.52, 7.05, 7.36, 9.36, 11.0, and 12.5 p ; n m r T 4.68 (br s , =CH), 6.23 (t, -CHzOH), 6.43 (5, -OH), Utilization Research and Development Division, U. S. 8.38 (>C=CCHa), and 9.13 (d, saturated CHs). Department of Agriculture, Agricultural Research Anal. Calcd for CllH200: C, 78.51; H, 11.98; mol wt, 168.27. Service. Found: C, 78.59, 78.46; H, 11.91, 12.02; mol wt, 164 (chloroform). (6) J. G. Burtle and W. N. Turek. J . Org. Cham., 19, 1507 (1954). Catalytic hydrogenation of the alcohol 7 with either Adams (7) Criterion for solubility: solution of 50 mg of polymer in 10 ml of catalyst or platinum black gave the saturated alcohol 6 that solvent after vigorous stirring for 0.5 hr at room temperature. was comprised of the same mixture of cis and trans isomers previ(8) Intrinsic viscosity measurements were kindly performed in the research laboratory of the Rohm and Haas Co., Bristol. Pa. ously described.
